This indicates 4K resolution (Ultra High Definition), which provides the highest level of detail available for home viewing.
These files or the sites hosting them often contain viruses, ransomware, or "adware" that can infect your device.
The file format (Matroska Video), which is a common container for high-quality video, audio, and subtitle tracks. Safety & Security Warning
"2160p" tags are sometimes faked or poorly compressed, leading to a worse experience than official streaming.